ChemInform Abstract: Photoinduced Molecular Transformations. Part 134. Photoinduced Stereospecific Addition of Methanol to 5β‐Cholest‐1‐en‐3‐one Oxime and Photoinduced Deconjugation of Its 1‐Methyl Derivative Involving Stereospecific Proton Transfer.

Abstract

Photoinduced Molecular Transformations. Part 134. Photoinduced Stereospecific Addition of Methanol to 5β-Cholest-1-en-3-one Oxime and Photoinduced Deconjugation of Its 1-Methyl Derivative Involving Stereospecific Proton Transfer.-Photolysis of 5β-cholest-1-en-3-one oxime (I) in MeOH affords products arising from a stereospecific photoaddition of MeOH and new skeletal rearrangement of the photogenerated parent ketone. However, no isoxazole derivative, which is formed in the photolysis of the 5. alpha.-isomer, is detected. On the other hand, irradiation of the 1-methyl derivative (VI) in MeOH results in a photoisomerization in analogy to its 5α isomer giving the β,γ-unsaturated isomer (VII). Labeling studies indicate that the principal reaction of steroidal 1-en-3-one oximes upon irradiation in MeOH is a stereospecific addition of MeOH or a proton to the photogenerated, twisted ground-state double bond of the oxime from the rear side of the steroidal framework. -(SUGINOME, H.; NAGAOKA, A.; SENBOKU, H.; J. Chem.